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bubblelestanks revisited - 5/3/2002 9:12:55 AM   
lon53lhc


 

Posts: 21
Joined: 3/22/2002
From: Lake Havasu City, Az
Status: offline 		OK, after reading all I could about the subject I went out and bought baby bottle liners, a new 4 oz tank, a clamp and a top of the line Martha Stewart turkey baster. Well, I quickly found out that a 4 0z tank was too small (I could get only about 3 0z of fuel in it using 4 oz liners) so I got an old 6 oz tank and 8 0z baby liners to experiment with, and instead of using fuel, I decided to use water to work out the bugs (in both the system and my technique). After venting the tank by punching a whole in it (This will be replace with a pressure fitting) and sealing up the 2nd hole in the stopper, I proceeded to practice filling the tank. For one thing, I could not get ALL the air out, no matter what I tried. I could get most of it out, but not all of it. The fuel line has air in it that cannot be sucked out because of its rigidity. So, my question is, how does one get ALL the air out? Or is it really necessary. I am using the usual fuel tank clunk, but I think the same thing can be accomplished by just slitting the pick-up fuel line to prevent blockage of which I read about in another post.

Thanks,

Lon
       Post #: 1

bubblelestanks revisited - 5/3/2002 9:55:32 AM   
JohnBuckner



Posts: 4047
Joined: 12/23/2001
From: Kingman, AZ, USA
Status: offline 		Hey Lon glad to hear you guys are experimenting down there, this is a good sign.

You did not say if you are using a fueling syringe or not. Without it it is virtually impossible to remove all the air. The Tetra's come with a set of instructions to use a normal pump and a third vent line with a complicated fueling senario that is just pointless, best to obtain a syringe of some sort.

Even with the syringe you will get sometimes a tiny amount of air but this is so little that it is impossible for vibration to whip this into sufficient foam to cause any problems.

Probably not a good idea to use a clunk or any other hard object in the bladder just a piece of metal tube extending into the middle of the tank that has a short piece of fuel tube extending about a quarter inch beyond the end. This is very improtant to prevent bladder puncture with even a slightly firm arrival.
Its for this reason that using a pressure fitting on a standard tank is not a good idea simply because it will tend to puncture the bladder. The Tetra pressure fitting is moulded in a way that the bladder cannot get to it. Also the baby bottle liner is more fragile than the regular bladder.

At fourteen dollars for the four oz tetra it would probably be best to buy one then with the first bladder failure from those firm arrivals modify to use the bottle liners (nothing else to buy beyond the liners themselves).

The one I tryed seems to work fine but have only used it on a test stand so far and probably the first ship to use it will be that Ukie float plane, You remember that one?

At your next slow quickee race I,ll bring a Tetra down with the bottle liner in it for you to check out and mess with.

Gotta load up now, heading for Whittier Narrows tomorrow and the new Midwing is working good.

John

_____________________________

"Keep your controllines tight"

(in reply to lon53lhc)
       Post #: 2

bubblelestanks revisited - 5/3/2002 9:56:23 AM   
PylonWorld



Posts: 1346
Joined: 12/29/2001
From: Monroe, NC, USA
Status: offline 		Don't use the clunk. Notch the pickup line on two sides about 1/16" x 1/16".

I'll see if I can take some pictures and/or post some details sometime in the next day.

How big in diameter is the turkey baster? More than likely you can't create enough of a vacuum with the TB.

_____________________________

Don Stegall
RCPRO Chairman of the Board

(in reply to lon53lhc)
       Post #: 3

bubblelestanks revisited - 5/3/2002 10:04:44 AM   
JohnBuckner



Posts: 4047
Joined: 12/23/2001
From: Kingman, AZ, USA
Status: offline 		Cool, Ok now I know what a turky baster is, boy do I feel like an airhead! If that won,t do it Lon How about just pooling the bucks and spend the thirty on a Jett tanker and then share it. Not really a problem with the number of people.


John

_____________________________

"Keep your controllines tight"

(in reply to lon53lhc)
       Post #: 4

bubblelestanks revisited - 5/3/2002 11:03:24 AM   
lon53lhc


 

Posts: 21
Joined: 3/22/2002
From: Lake Havasu City, Az
Status: offline 		Yeah, John, this is a premium quality one from Martha Stewart! It has a real big bulb and a brushed aluminum body. My wife is very envious! It has plenty of suction power. I also tried to pop one of the baby bottle liners, and it took a series of very hard slaps when blown up like a paper bag before it popped. If I pop one of these while in the plane, there would not be much left of that plane to worry about. Pylonworld, thanks for the tip about the pick-up, I will not use one. John, that is a good idea about buying a Jett tanker. I personally do not mind the investment, but I am running an entry level event, and if some newbe finds out it cost almost 50 bucks for a fuel tank system, that might be a bit much.

Thanks, and good luck at Whittier!

Lon

(in reply to lon53lhc)
       Post #: 5

bubblelestanks revisited - 5/3/2002 11:21:27 AM   
lon53lhc


 

Posts: 21
Joined: 3/22/2002
From: Lake Havasu City, Az
Status: offline 		Just found out the TB holds exactly 4 oz of fluid. I have pressure tested it and there is a very small leak at the tip where it screws into the tube. That will be easy to seal. The bulb itself slips on at the other end and is just a firm fit which I used a tyrap to seal, and that is not leaking even under extreme pressure. I am getting pretty good at filling the tank up with out much waste, and the air bubble is pretty small. It might just work.

Lon

< Message edited by lon53lhc -- May 3 2002 6:30AM >

(in reply to lon53lhc)
       Post #: 6

bubblelestanks revisited - 5/3/2002 11:26:31 AM   
lon53lhc


 

Posts: 21
Joined: 3/22/2002
From: Lake Havasu City, Az
Status: offline 		Don, in regards to the pressure fitting could be trouble, I have a tank that a member of our club built, and he tapped the fitting into the bubble at the top of a Sullivan tank. I used my finger to feel around, and I could not feel any metal. He use RTV to seal and protect the bladder.

Lon

(in reply to lon53lhc)
       Post #: 7

bubblelestanks revisited - 5/3/2002 8:54:36 PM   
js3



Posts: 1147
Joined: 1/30/2002
From: Arvada, CO, USA
Status: offline 		How about just using standard 4 oz tanks for the slow quickie class and bagging the whole bubbless tank system? No muss, no fuss. Everyone already knows how to set them up and everybody already has the equipment to fill the tank.

After all, entry level racing is supposed to be easy.

_____________________________

John
I feel a lot more like I do now than I did earlier!

(in reply to lon53lhc)
       Post #: 8

bubblelestanks revisited - 5/3/2002 9:06:12 PM   
PylonWorld



Posts: 1346
Joined: 12/29/2001
From: Monroe, NC, USA
Status: offline 		Lon,

John brought up the pressure fitting issue.

On the Jett tanks, they don't even use a fitting ... they just drill a hole a little smaller than the pressure tubing (between 1/32" and 1/16" smaller and put the tubing in. It doesn't even look like they use any adhesive, and let the tubing silicone do the seal. I usually put some silicone around tubing to be sure it doesn't come out.

It's okay for the tubing to poke into the chamber by about 1/4" to 3/8" of an inch. The bladder doesn't seem to mind the soft silicone nub.

I have used a Mac Thin Wall pressure fitting on a home made tank. They don't have anything protruding that would hurt a bladder.

< Message edited by PylonWorld -- May 3 2002 9:25PM >

_____________________________

Don Stegall
RCPRO Chairman of the Board

(in reply to lon53lhc)
       Post #: 9

bubblelestanks revisited - 5/3/2002 10:07:46 PM   
lon53lhc


 

Posts: 21
Joined: 3/22/2002
From: Lake Havasu City, Az
Status: offline 		js3,
you are absolutley right, and that is my position to keep this event as simple as possible, but a couple of guys wanted to look at the possiblities of bubblesstanks because of the possible more consistant engines runs. Although, I think most flame outs we have had have been due to engines not broken in properly and a too lean needle setting. I read somewhere that if your engines sags in flight it is due to overheating from not being broken in, not from "leaning out" in the air. In fact, I think the author said that an engine could not lean out in level flight in the air if it was running good at operating temps on the ground before the flight. That is of course with a properly installed fuel system. But I am not an expert in this area.

But now that I have gone this far, I am actually having some fun from this learning experiance, whether we use it for racing or not.


Yeah you are right Don about John bringing up the pressure fitting issue, but it was late last night and I was not thinking too clearly! Thanks for the advice, anyway.

Lon

(in reply to lon53lhc)
       Post #: 10

bubble jett tanks - 5/3/2002 11:52:17 PM   
bob27s



Posts: 4924
Joined: 4/9/2002
From: Cleveland, OH, USA
Status: offline 		Bubble-free tanks are certainly an excellent, EASY addition even for sport racing. If the goal is to keep racing simple, using the tanks removes one of the biggest variables out there.... fuel systems. A slight big of foaming, a tiny air leak.... those things can drive experienced pilots nuts, and drive novice racers totally insane!

The engine runs are always consistant, you dont have to worry about blowing a plug if the fuel gets low. Glow plugs cost what... $3-4 each. Consider the investment in a tank and filler a decent trade between blowing a handfull of plugs. Even to a beginner, this tends to make sense.

Lon,
don't worry if you only are getting about 3 or 3.5 oz of fuel in your fuel tank. If a 4oz regular tank was enough in the past, the 3ozs will be enough. A regular 4oz tank might hold a total of 4oz, but when you get down to actual operating volume with a clunk, tubes installed, plus the safety margin you need to maintain(considered unusable fuel... for racing, about 1/4 of a tank) you basically only have 3 oz available. With a properly set up bubbleless tank, you can draw every last drop of fuel without worrying about the engine going lean. So, your 3oz bubble tank will get you just as far or further than a regular 4oz tank.

Jett will have 4oz tanks available shortly. Lots of requests from 424 and combat pilots. I will check on the availability date. Currently have 6oz (actually 5.5 oz) in three shapes, plus a 12oz available. The bladders he uses, when used properly with the fueler, will never wear degrade or break.

It is still best to use the jett fueler for filling bubble-free tanks of any kind. Its one of the best investments you can make for racing. Draw the air out, and put the fuel in all in one operation. It sure beats the older small syringe and having to clamp off the line between vent and filling operations. There are a few other similar products available. Each will do the job, and all are worth the investment.

Bob Brassell

(in reply to lon53lhc)
       Post #: 11

bubblelestanks revisited - 5/4/2002 4:58:51 AM   
lon53lhc


 

Posts: 21
Joined: 3/22/2002
From: Lake Havasu City, Az
Status: offline 		Bob, Thanks for your point of view. I could buy the jet fueler and let eveyone use it who wants to. You are right about the 3 oz being enough. Our Quickees are powered by .25 and .28s, and after every heat I defuel my plane and it has a little less than 1/2 tank. We use the "Reno" style start so the 1st airplane in the air has to wait for the others, and I still have a number of "cranks" of fuel left. Also, we have been flying a 1400 ft (total distance) 2 pin course for a long time and recently reduced it to about 1200, so 3 ozs should be plenty. I will also try using the 8 oz liners cut down to fit inside a 4 oz tank. That should solve the problem I had with a 4 oz liner.

Lon

(in reply to lon53lhc)
       Post #: 12

bubblelestanks revisited - 5/4/2002 5:14:22 AM   
PylonWorld



Posts: 1346
Joined: 12/29/2001
From: Monroe, NC, USA
Status: offline 		Lon,

As you've probably already read, it is important to clamp the fuel feed after filling the bladder, before detaching the tanker. You can use hemostats, but at least some people use inline fuel shutoff clips. They stay with the plane, and don't bang around.

The cheapest, easiest to use clips that I have found are carried by Horizon Hobby. The [URL=http://www.horizonhobby.com/products/description.asp?prod=KSJ221&pc=KSJ221]KSJ Fuel Shutoff Clips[/URL] are actually made by a helicopter manufacturer. You get 8 clips for $2.95, of which the breakdown is:

2 - Large
2 - Medium - perfect for medium tubing, slightly tight on the Prather tubing
2 - Small with a medium size slot
2 - Small with a small slot

You can make the smalls work with medium tubing with a little round file and thin flat file work. You can probably carve them out with an Xacto also.

I didn't have anything else I needed to order from Horizon and I was pleasantly surprised by the $4 S&H for Priority Mail for an order of 4 packs.

When you get ready to start the plane, just slip the clip, and start. Or have your helper slip the clip as you hit the spinner.

I think Dave Norman uses these also.

_____________________________

Don Stegall
RCPRO Chairman of the Board

(in reply to lon53lhc)
       Post #: 13

KSJ clips - 5/4/2002 5:45:28 AM   
daven



Posts: 7026
Joined: 12/7/2001
From: Andover, MN, USA
Status: offline 		The KSJ clips are the way to go in my opinion. It takes a little while to get use to unclipping them before you start the engine. Sometimes you forget they are there, and the engine won't start!

Hemostats are fine, but can be tough on fuel line. Also, you have to worry about misplacing them after you start the engine.

I wasn't aware there were 4oz jett tanks coming out. Thats good to hear, they really make a big distance in keeping your needle consistant for all 10 laps. I've got the 5.5 - 6oz tanks in most of my 424 racers, and I would love to dump 2oz of fuel.

_____________________________

Dave Norman

klasskote.com
supertrc.com

(in reply to lon53lhc)